1. Field of the Invention
The present invention relates to a call control server that connects a communication terminal to another terminal.
2. Description of the Related Art
With the implementation of the Act on the Protection of Personal Information, leakage of personal information has become a social problem. In particular, there has been a case where personal information is erroneously transmitted to a wrong destination through communication by, for example, facsimile.
As a countermeasure against this problem, some banks have introduced a system to prevent leakage of client information due to facsimile erroneous transmission. Reference may be had to the site, http://www.kyotobank.co.jp/news/pdf/2005_07_21.pdf (accessible as of Oct. 6, 2005). In this system, data is transmitted from a facsimile machine via a local-area network (LAN) in the bank to a facsimile server, where the data is automatically checked with destination information (destination name, facsimile machine number, etc.) registered in advance.
If they match and the destination is a place outside the bank, transmission is temporarily halted and an executive in a transmitting section checks the destination and contents to be transmitted on a personal computer (PC) screen, and then originates a call to a public line.
In this system, however, although the destination information of a place outside the bank is double-checked through an automatic check on the facsimile server and a visual check by human, the source information is checked only through a visual check by human (this operation is not explicitly explained, but it is assumed that the source information is checked through a check of transmission contents by human; absence of a source check is not certain). That is, the transmission source and the transmission destination are checked by human.
In this case, human check may suffice if the number of transmission sources and transmission destinations is relatively small. However, if the number is increased, reliability of human check is decreased, causing problems such that personal information is transmitted to an unintended destination, leading to leakage of the personal information to third parties. Moreover, in this case, there is also a problem that such a human check takes time, thereby impairing a real-time feature of facsimile communication to interfere with business.
Meanwhile, even among sections using a closed corporate network, there is a risk in which a document is erroneously transmitted to a destination (section) not pertinent to personal information written on the document, leading to erroneous leakage of the personal information to third parties without an appropriate process at the section receiving the document image.
Japanese Patent Application Laid-Open Publication No. 2004-289782 discloses a method in which, at the time of IP packet transfer over a network, a source address and a destination address in an IPv6 header of an IP packet are identified, and when interface IDs in the source address and the destination address match with a preset condition, a transfer over the network is permitted or prohibited correspondingly. This interface ID contains information, such as apparatus type, and a manufacture name and apparatus model can be used as filter conditions.
However, this operation can be applied only to a gateway, and cannot be directly applied to a call control server for call connection.
Therefore, other than communication via this gateway, erroneous facsimile transmission cannot be prevented, resulting in a problem that personal information is leaked to third parties.
Normally, when personal information is leaked to third parties through erroneous facsimile transmission, it is desirable that the transmitting operator can be specified.
However, in the conventional technologies explained above, a check to see who is a transmitting operator cannot be performed. Therefore, when a problem of leakage of personal information occurs, it is difficult to specify a transmitting operator, thereby causing the ultimate location of responsibility to be blurred and posing a problem such that a risk of repeating the same error remains.
The problems explained above may occur not only in personal information, but also in corporate confidential information.
On the other hand, in recent years, equipment and systems for transmitting and receiving voice data over a Voice over IP (VoIP) network have started to become widespread. Also, needs for performing facsimile communication over this VoIP network is being increased, and facsimile communication systems have been used, such as the one conforming to International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Recommendations T.38 optimal to an IP network and the one in a G.711 PassThrough scheme in which a facsimile signal is regarded as a voice signal and is packetized to flow through an IP network.
In an in-company VoIP network in place of Private Branch Exchange (PBX) used in a conventional analog circuit, a call control server is often used, in which a call is switched on an IP-packet base. In this case, a call to be switched is usually an IP-phone call, and there are not so many facsimile calls compared to IP-phone calls. For this reason, when an additional operation is performed only for controlling facsimile calls, it is desired that whether to perform this additional operation be determined based on information from the calling source.